"The mountains are calling, and I must go." —John Muir

Spike!

You know you’re out of shape when your heart rate spikes up to 2 bps below your theoretical max HR based on one methodology and 3-4 bps higher than your max HR based on the 220-age methodology, when riding a relatively flat route.

I’m not seeing to 220+ rates that the Doctor is getting, but I still find the numbers disconcerting.